In the past 15 years, insights in clinical and genetic characteristics of Parkinson disease
(PD) have increased substantially. Sequence or copy number variants in at least six genes
(SNCA, LRRK2, PARK2, PINK1, DJ-1 and ATP13A2) have been identified to cause
monogenic forms of PD. Routine clinical testing for mutations in these genes is feasible and
available, but overlapping phenotypes in monogenic and sporadic PD complicate
straightforward diagnostic screening. Primarily, a positive familial history and an early onset …